Modified Stock Gearing - Boston Gear
Modified Stock Gearing - Boston Gear
Modified Stock Gearing - Boston Gear
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Miter & Bevel <strong>Gear</strong>s<br />
<strong>Boston</strong> stock miter and bevel gears are designed for transmission of power<br />
and/or motion between intersecting shafts at a right angle (90°). Miter gears are<br />
a special type of bevel gear designed to operate as pairs being identical in<br />
number of teeth and pitch (1 to 1 ratio only). Other <strong>Boston</strong> stock bevel gear sets<br />
are available with ratios from 1-1/2:1 to 6:1.<br />
All <strong>Boston</strong> standard stock bevels and miters are manufactured with a 20°<br />
pressure angle. These bevel gears are made in accordance with AGMA<br />
specifications for a long and short addendum system for gears and pinions,<br />
which serves to reduce the amount of pinion tooth undercut and to nearly<br />
equalize the strength and durability of the gear and pinion. <strong>Boston</strong> straight tooth<br />
bevel and miter gears have generated teeth with “Coniflex” ® tooth form, unless<br />
otherwise specified.<br />
INTERCHANGE<br />
<strong>Stock</strong> miter and bevel gears having identical diametral pitch, number of teeth<br />
and mounting distance (and spiral angle for spiral bevels) are interchangeable.<br />
SPIRAL VS. STRAIGHT TOOTH<br />
<strong>Boston</strong> standard stock straight bevel gears can be used for all applications<br />
requiring transmission of power and motion between intersecting shafts. <strong>Boston</strong><br />
standard stock spiral bevel gears have an overlapping tooth action which<br />
results in a smoother gear action, lower noise, and higher load capacity than a<br />
straight bevel of equal size.<br />
®Trademark of the Gleason Works.<br />
Selection Procedure<br />
Approximate horsepower ratings for selected sizes (number<br />
of teeth) at various operating speeds (RPM) are given for<br />
<strong>Boston</strong> standard stock Bevel and Miter gears.<br />
For straight tooth Miter gears, refer to Pages 80, 81.<br />
For straight tooth Bevel gears, refer to Page 82.<br />
For spiral tooth Miter gears, refer to Page 83.<br />
For spiral tooth Bevel gears, refer to Page 83.<br />
All ratings are based on normal operating conditions, that is:<br />
properly mounted and lubricated, carrying a smooth load for<br />
not more than 10 hours (Service Factor = 1.0). Refer to Table 1<br />
for service factors in other service conditions.<br />
1. Determine service factor.<br />
a. Using Application Classification Chart I, pages 323-324<br />
determine service factor or<br />
b. With knowledge of operating conditions and load<br />
classification, select service factor from Table 1.<br />
2. Determine Design Horsepower.<br />
Design HP = Application Load x Service Factor (Table 1)<br />
3. Select a gear set with horsepower capacity equal to (or<br />
greater than) design horsepower determined in Step 2.<br />
C<br />
TABLE 1<br />
Service<br />
Factor<br />
Operating Conditions<br />
.8 Uniform — not more than 15 minutes in 2 hours.<br />
Moderate Shock — not more than 15 minutes in 2 hours.<br />
1.0<br />
Uniform — not more than 10 hours per day.<br />
Moderate Shock — not more than 10 hours per day.<br />
1.25<br />
Uniform — more than 10 hours per day.<br />
Heavy Shock — not more than 15 minutes in 2 hours.<br />
1.50<br />
Moderate Shock — more than 10 hours per day.<br />
1.75 Heavy Shock — not more than 10 hours per day.<br />
2.0 Heavy Shock — more than 10 hours per day.<br />
Heavy shock loads and/or severe wear conditions may<br />
require the use of higher service factors. Consultation with<br />
factory is recommended in these applications.<br />
P-1930-BG 04/10 <strong>Boston</strong> <strong>Gear</strong> 800-825-6544 79